Photoresponse Properties Of Ultrathin Bi₂Se₃ Nanosheet And Its Hybrid Material

Range of nanomaterials research is very broad, covering a very rich field from its radical material into nanoparticles and nanowires and then extended to the development of ultra-thin two-dimensional structure of the material. After the birth of graphene, topological insulators(TI) as a new type of quantum functional materials, have aroused the attention of domestic and foreign scholars and researchers, and a number of important research results have been published. Our work is mainly for the preparation, characterization and photoresponse properties of bulk Bi2Se3, as-prepared Bi2Se3 nanosheets and Ag/Bi2Se3 hybrid composite. The full text is divided into five chapters:The first chapter describes the common preparation methods, properties, and applications of graphene, transition metal disulfide compounds and topological insulator, and analyzes the problem which still exists and the future developments.The second chapter describes in detail the use of a simple hydrothermal intercalation and exfoliation route to obtain Bi2Se3 nanosheets and analyzes the structure and characterization of the samples. We successfully obtained the large Bi2Se3 nanosheets which have uniform thicknesses of 2-3 nm and have high purity with high crystallinity.In the third chapter, we mainly study the photoresponse of the bulk Bi2Se3, the as-prepared Bi2Se3 nanosheets and the Bi2Se3 nanosheets after annealing. Compared with the other two samples, the as-prepared Bi2Se3 nanosheets possess a dramatically enhanced photoresponse with very fast response time, superior current response and external quantum efficiency.In the forth chapter, we successfully fabricated the Ag/Bi2Se3 hybrid composite, in which Bi2Se3 nanosheets were used as substrate anchored by Ag nanoparticles. Compared with pristine Bi2Se3 nanosheets, the as-synthesized Ag/ Bi2Se3 nanocomposite exhibited a significant enhanced photoresponse performance.The fifth chapter is the summary of my research and key achievements. In this chapter, we also discuss the deficiency of our current investigation and prospective research directions.